Expose max_new_tokens run option

[vladkalinichencko]

This exposes a per-run max_new_tokens option through the C API and all generated language bindings.

Some autoregressive ASR families can accept the audio input but still hit the fixed generation budget before emitting EOS. That returns OUTPUT_TRUNCATED with a partial transcript, but callers previously had no way to request a larger output budget.

The default behavior stays unchanged: non-positive values use the existing family defaults. Qwen3-ASR and Canary honor a positive value for single and batch runs, bounded by the decoder context.

Rebased onto the current main / 0.2.0 API, preserving the newer diarization fields and generated ABI.

Validated with:

• Python and Rust binding-generator checks
• Swift ABI hash check
• cargo fmt --all --check
• cargo check -p transcribe-cpp
• TypeScript typecheck
• native CMake build and transcribe_api_smoke test

[cjpais]

Thanks I will take a look tomorrow

[cjpais]

Sorry, it's taking me a bit longer to review this since it's a header change. I will want to take a closer look, which will just take some time

[vladkalinichencko]

No worries, thanks. I have rebased this onto the current main / 0.2.0 API, regenerated every binding and the Swift ABI hash, and rerun the native C API smoke test plus the Rust, TypeScript, Python, and Swift checks. The companion Handy PR cjpais/Handy#1633 is also rebased and conflict-free.

[cjpais]

ill be reviewing this and pulling in soon, thank you!

[cjpais]

I just want to say I appreciate you submitting this. I have definitely thought quite a bit about it and I think the bigger issue here is we shouldn't have done this in our implementation to begin with, and it's a bug in the fundamental implementation itself. And I don't think exposing this knob clarifies things or makes the API better. So I think I'm going to close this because fundamentally this is just a bug in the code itself. And I think more or less all of this can fall under the n_ctx flag where necessary, and we can remove our broken internal implementation which hardcodes these values